Acetazolamide-related compounds, process for their preparation, and pharmaceutical composition containing the same

ABSTRACT

Compounds related to acetazolamide and to its N-methyl derivatives, of the formula: ##STR1## wherein Y is one of the following groups: ##STR2## R 1  being a straight or branched alkylene or arylalkylene, or a phenylene, and the processes for their preparation; the compounds so obtained are inhibitors of carbonic anhydrase like acetazolamide but, in addition, they are well absorbed topically so that they can be used as drugs for treating glaucoma.

This is a divisional of copending application(s) Ser. No. 07/381,453filed on Jul. 18, 1989, now U.S. Pat. No. 5,010,204.

This invention relates to novel acetazolamide-related compounds havinginhibiting activity on carbonic anhydrase, which are useful inparticular for treating glaucoma. More particularly, this inventionrelates to novel agents capable of inhibiting carbonic anhydrase, whichare characterized in that they can be well absorbed locally, so thatthey are particularly suitable for topical administration.

The term glaucoma commonly means a variety of clinical conditions whichare characterized by a progressive increase in intraocular pressure, acondition which gives rise to severe defects in the eye structures, upto optical atrophy. Various kinds of primary and secondary glaucoma areknown, but all forms show a common feature, i.e. the increase of aqueoushumour in the anterior chamber of the eye (camera anterior bulbi).

Various drugs are known that are capable of reducing the intraocularpressure, so that they could be employed for treating glaucoma, buttheir efficiency is variable and all of them show more or less seriousside effects. Among such drugs, there are compounds showing cholinergicaction (acetylcholine, pilocarpine and eserine), having a short-lastingaction, compounds showing anticholinergic action, with remarkable sideeffects (atropine), compounds with adrenergic action (adrenalin), whichare effective but painful, and compounds with antiadrenergic action(adrenergic beta-blocking agents).

These last compounds are the most commonly employed: thymolole, anadrenergic beta-blocking agent, is the most diffused product presentlyan the market in many countries; however, this class of drugs is alsoaffected by undesired side effects, such as fits of asthma and cardiactroubles.

An additional class of compounds capable of reducing intraocularpressure, and therefore potentially useful for treating glaucoma, is theclass of carbonic anhydrase inhibitors, the best known-among them beingacetazolamide. These compounds, though remarkably efficient, cannot beabsorbed topically, so that they are to be administered systemically,and in particular through the oral route.

Systemic administration-of such drugs, and, in particular, ofacetazolamide, is however affected by a number of side effects, such asa feeling of weariness, gastrointestinal troubles and anorexia, due tothe diuretic action of such drugs. Their effects are so severe,especially at the kidney level, that their employment for treatingglaucoma is impossible as a matter of fact.

Accordingly, this invention relates to the object of providing novelcompounds capable of inhibiting carbonic anhydrase, which compounds, inaddition to showing an activity comparable to that of acetazolamide,also are characterized by being well absorbed locally, so that they canbe employed by administration through the topical route. It is quiteclear that topical administration allows to obtain a therapeutic actionwithout the noxious side effects given by the drug itself when it isadministered through the systemic route.

Accordingly, we have devised to modify the molecule of acetazolamide soas to increase both their water solubility and their lipophiliccharacter. As a matter of fact, acetazolamide is practically insolubleand lacks lipophilic groups, its poor absorption when instilled in theeye being ascribable to both such factors.

Accordingly, the present invention provides sane compounds related toacetazolamide or to its N-methyl derivatives, which contain a lipophilicacylic chain bearing at its other end an esterified orunesterified-carboxylic group, an amino group or a phthalimido group.

Accordingly, the present invention specifically provides compoundsrelated to acetazolamide or to its N-methyl derivatives, capable ofinhibiting carbonic anhydrase, said compounds having the formula:##STR3## wherein Y is one of the following groups: ##STR4## wherein R₁is a straight or branched alkylene or aryl-alkylene or a phenylenegroup, R₂ is hydrogen or a straight or branched alkyl optionallysubstituted with halogen, R₃ and R₄, which are the same or differentfrom one another, are hydrogen or a straight or branched alkyl, as wellas the physiologically acceptable salts thereof.

More particularly, the specific objects of the present invention are thecompounds having the formulas (I), or (II), or (III) wherein Y has onethe following structures:

    R.sub.2 OCO--(CH.sub.2).sub.n --

wherein R₂ is hydrogen or a straight or branched alkyl having 1-20carbon atoms and optionally substituted with halogen, n being an integerbetween 1 and 10; or: ##STR5## wherein R₂ has the same meaning as above;or: ##STR6## wherein R₃ and R₄, which are the same or different from oneanother, are hydrogen or a lower alkyl of 1-6 carbon atoms, n being aninteger between 1 and 10; or: ##STR7## wherein both R₃ and R₄, as wellas n have the same meanings as above.

The compounds disclosed above can also be in the form of theirphysiologically acceptable salts, both of bases and of acid, eitherorganic or inorganic.

Examples of suitable bases are sodium hydroxide, potassium hydroxide,calcium, barium and ammonium hydroxides.

Hydrogen halides, sulfonic acid, phosphoric, nitric, perchloric acid,and aliphatic, cycloaliphatic, aromatic or heterocyclic carboxylic andsulfonic organic acids such as formic, acetic, propionic, succinic,glycolic, lactic, malic, tartaric, citric, ascorbic, maleic,hydroxymaleic, piruvic, phenylacetic, benzoic, paraaminobenzoic,anthranilic, p-hydroxybenzoic, salicylic, p-aminosalicylic, pamoic,methansulfonic, ethansulfonic, hydroxyethansulfonic, ethylensulfonic,halogenobenzensulfonic, toluensulfonic, naphthalensulfonic, andsulfonylic acid are particularly suitable to form salts forpharmaceutical employment.

The novel active compounds of the present invention keep the property ofenzymic inhibitor typical of acetazolamide, and.,at the same time, theyare more soluble and more lipophilic with respect to acetazolamidebecause of the presence in their structures of the modifier group Y.Therefore, they are much more absorbable topically.

Moreover, among such compounds those which have in their chain anesterified carboxyl group have a further feature that makes themparticularly interesting for topical treatment of glaucoma: due to theaction of esterases that are present in the ocular tissue, they giverise to a principal metabolite with a free carboxyl group. The latter,as a result of its physicochemical characteristics, has a poor tendencyto pass into the plasma and to spread throughout the organism. Thiscontributes to reduce the possibility that the novel compounds exert asystemic action and hence this contributes to reduce the possibility ofoccurrence of side effects.

The following table 1 reports some results of in vitro activity tests ofthe compounds of the present invention; beside the solubility in abuffer at pH=7.6, there is shown the value of the molar concentrationthat gives a 50% reduction of enzymic activity (I₅₀): as can be clearlyseen, the in vitro activity of the compounds of the present invention iscomparable to or better than that of acetazolamide.

                  TABLE 1                                                         ______________________________________                                                            Solubility in                                                                 buffer pH                                                 COMPOUND            7.6 (mg/ml)                                                                              I.sub.50 × 10.sup.-7                     ______________________________________                                        ACETAZOLAMIDE       --         4.4                                            RENDE 023           0.74       5.5                                            Series I, Y═CH.sub.3 OCO--(CH.sub.2).sub.2 --                             RENDE 024           2.25       4.5                                            Series III, Y═CH.sub.3 OCO--(CH.sub.2).sub.2 --                           RENDE 027           0.208      4.4                                            Series I, Y═NH.sub.2 --(CH.sub.2).sub.4 --                                RENDE 029           2.76       7.3                                            Series I,                                                                     Y═CH.sub.3 CH.sub.2 OCO--(CH.sub.2).sub.2 --                              RENDE 032           0.47       3.9                                            Series I,                                                                     Y═CH.sub.3 (CH.sub.2).sub.4 OCO--(CH.sub.2).sub.2 --                      RENDE 034           1.24       3.7                                            Series I,                                                                     Y═(CH.sub.3).sub.2 CHCH.sub.2 OCO--(CH.sub.2).sub.2 --                    RENDE 035           0.535      3.07                                           Series III,                                                                   Y═CH.sub.3 (CH.sub.2).sub.4 OCO--(CH.sub.2).sub.2 --                      RENDE 037           28.7       5.5                                            Series I, Y═HOCO--(CH.sub.2).sub.2 --                                     ______________________________________                                    

For determining the in vitro activities, samples were employed at molarconcentrations of 10⁻⁷, 3×10⁻⁷, 6×10⁻⁷, and 10⁻⁶, and the results givenin Table 1 were obtained by CO₂ -electrode potentiometric analysis.

In vivo experiments were carried out on the compounds of the presentinvention, and, amongst the others, those experiments whose results arereported in the following Table 2, concerning the decrease in the ocularpressure in rabbit.

For determining such results a transient ocular hypertension model wasemployed, said hypertension being obtained in rabbit through rapidvenous infusion of suitable volumes (20 ml/kg) of 5% glucose solution.

Albino rabbits from the same farm in New Zealand were employed, whoseweights were between 2,,500 e 3,,000 g. Each treatment was carried outon a group of six animals.

The drug was prepared in a phosphate buffer water solution at pH 7.5.The solution was made isotonic with sodium chloride and the possibilityof microbial contamination was prevented through the addition ofbenzalkonium chloride. In case of compounds of low solubility, adispersing suspension of the finely divided compound in methyl cellulosewas prepared. The solution (or the suspension) was instilled into theright eye of each animal in the amount of 2 drops of 2% solution, at aninterval of 2 minutes from one another. The left eye was treated with anequal volume of diluent.

The measurements of pressure were performed while animals were insuperficial local anaesthesia (0.4% benoxinate), by means of aMcKay-Marg electronic pressure gage, at the times -30', 0', 10', 20',40'.

The following table reports the endoocular pressure measured after 10,20, and 40 minutes both in the right and in the left eye: the higher thedifference in the ocular pressure between the treated eye and theuntreated eye, the higher the efficiency of the drug considered.

                  TABLE 2                                                         ______________________________________                                               mmHg                                                                          10'       20'         40'                                              Compound 0D      0S      0D    0S    0D    0S                                 ______________________________________                                        RENDE 023                                                                              25.33   25.5    19.5  20.17 16.5  16.67                              RENDE 024                                                                              24.67   25.83   20.33 21.5  17.33 17.83                              RENDE 027                                                                              24.0    26.17   20.83 21.5  16.83 17.33                              RENDE 029                                                                              20.33   25.67   17.33 20.67 15.67 17.67                              RENDE 032                                                                              22.67   24.5    20.0  21.33 17.83 18.83                              RENDE 034                                                                              21.5    25.67   19.0  21.17 16.67 17.17                              RENDE 035                                                                              24      25.17   20.67 22.0  17.83 18.0                               RENDE 037                                                                              19.33   26.0    17.17 21.67 15.67 19.0                               ______________________________________                                    

The derivatives proposed by the present invention can be employed forpharmaceutical purposes and can be administered topically orsystemically as such or in the form of salts. They can be employed notonly for the topical or systemic treatment of glaucoma, but also asdiuretics, anthypertensive and vasodilating agents.

The products of the present invention and their salts can be employed inthe form of pharmaceutical preparations with liquid or solid, organic orinorganic excipients, which are suitable for the topical, oral orparenteral administration. Suitable excipients are pharmaceuticallyacceptable compounds that do not interfere with the activity of thecompounds of this invention, such as water, cellulose, surface activeagents, gelatins, lactose, talc, starch, magnesium stearate.

Moreover, the pharmaceutical preparations, which can be collyria,tablets, capsules, pills, solutions, suspensions. emulsions, ointments,creams and suppositories, can also contain preserving agents, as well asstabilizing, wetting, emulsifying, solubilizing agents and salts foradjusting the osmotic pressure and the pH value.

The present invention also relates to some methods for preparing thecompounds disclosed above.

A first group comprises methods which, although different in somedetails depending on the structure of the product to prepare, all startfrom the 5-amino-2-mercapto-1,3,4-thiadiazole and comprise threefundamental steps: the acylation step of the amino group of the startingcompound, the oxidation step of the mercapto group to the correspondingsulfonyl, and the reaction step with ammonia to obtain the correspondingsulfonamide.

The specific method of this group for preparing the compounds of theseries I wherein Y is the group

    R.sub.2 OCO--R.sub.1 --

is disclosed with its variants in the following scheme A:5-amino2-mercapto -1,3,4-thiadiazole is subjected to acylation (step a),employing as acylating agents the hemiesters of bicarboxylic acids ofthe formula:

    R.sub.2 OCO--R.sub.1 --COOH

or the acid halides of said esters having the fomula:

    R.sub.2 OCO--R.sub.1 --COX

wherein X is a halogen atom, or asymmetric diesters of the formula

    R.sub.2 OCO--R.sub.1 --COOR'

or the anhydrides of the hemiesters as above, of the fomula: ##STR8## orthe cyclic anhydrides of the bicarboxylic acid, of the formula:

In the formulas reported above, R₂ is different from hydrogen. In theparticular instance in which the final desired product has R₂ ═H, anyesterified acylating agent can be employed , and the terminal carboxylicgroup is liberated at the end of the process through saponification byprolonged treatment with a strong alkali. In particular, the compound istreated with NAOH for at least 2 hours it room temperature. ##STR9##

The acylation reaction a) can be carried out in a suitable organicsolvent, preferably in anhydrous tetrahydrofurane (THF) or methylenechloride, under nitrogen at room temperature and employing as a catalystan organic base, generally triethylamine with small amounts of4-dimethylaminopyridine (DMAP).

The oxidation of the mercapto group (step b) is performed preferablywith a gaseous halide (X₂) in acetic acid at low temperature, generallyat 1° C.; under these conditions, the sulfonyl halide is formeddirectly. Such compound, after extraction with an organic solvent orfiltration in case it is a solid, is reacted with liquid ammonia (stepc).

The reaction step c)is carried out at a very low temperature, preferablyat -78° C., under nitrogen.

The reaction product is purified through direct crystallization orthrough dissolution in a weak,- basic medium and successiveprecipitation with an acid, preferably with hydrochloric acid at pH 4.

In alternative to the process consisting of the steps a), b) and c) itis possible to protect the mercapto group through benzylation (step d)before performing the acylation of the amino group. Such operation canbe carried outfor instance by reacting the starting compound with benzylbromide (BrCH₂ Ph) in ethanol in the presence of elemental sodium.

After acylation (step a'), the benzyl group can be removed by treatmentwith elemental sodium in anhydrous ethyl alcohol and bubbling CO₂ (stepe'). In that case, the preparation process is completed through thesteps b) and c).

Alternatively, the benzyl derivative is subjected directly to theoxidation of the substituted mercapto group to sulfonyl halide (step b')under conditions similar to those disclosed for the oxidation step b);the process ends with the step c).

A further route of synthesis according to the scheme A consists insubjecting the starting compound to acylation (step a), and thenperforming the benzylation of the mercapto group (step e) followed bythe oxidation (step b') and the treatment with ammonia (step c).

Again according to the present invention, the specific process forpreparing the compounds of the series I wherein Y is the group ##STR10##wherein n has the same meaning as in the preceding case, and R₃ and R₄,which are the same or different from each other, are hydrogen or astraight or branched alkyl chain, is disclosed in the following schemeB: the 5-amino-2-mercapto-1,3,4-thiadiazole is first benzylated in themercapto group as in the reaction Step d) of the preceding scheme, andthen it is subjected to acylation of the amino group with thehalogenated carboxylic acid chloride of the formula:

    X--R.sub.1 --COCl

wherein X is a halogen atom and R₁ is the chain desired to be present inthe final group Y. ##STR11##

The acylating agent X-R₁ COCl can be obtained according to thepreparation step f)by reacting the corresponding halogenated carboxylicacid with thionyl chloride (SOCl₂).

After the acylation step a)of the benzylated starting compound, which iscarried out according to the same operational modes as those employed insteps a)and a') of the scheme A, the oxidation step of the mercaptogroup (step b) is performed, which step is similar to the step b) of thescheme A.

The compound so obtained, treated with liquid ammonia (step c) as in thestep c) of the scheme A, is subjected to the substitution, both of thehalogen atom in the sulfonyl halide group and of the halogen atom boundto R₁, with two amino groups.

In case R₃ and/or R₄ in the desired product are different from hydrogen,the mono-alkylation or di-alkylation of the amino group of Y (step g) isfinally performed.

The specific process for producing the compounds of the series I whereinY is the group ##STR12## wherein R₁, R₃, and R₄ have the meaningsalready known, is illustrated with its variants in the following schemeC.

A possible route of synthesis is that of proceeding in the same way asthat shown in the scheme B, steps d), f) and a), thus obtaining a benzylmercaptan which is acylated in the amino group with the chain X--R₁--CO--, and, in a second step, of introducing the phthalimido group asthe terminal group in said chain through the reaction with the desiredpotassium phthalimide (step h). ##STR13##

Starting from that point, the oxidation of the benzylmercaptan group andthe treatment with ammonia are similar to the steps of the precedingschemes (steps b) and c).

Alternatively, the phthalimido group can already be present in theinitial acylating agent, so that the acylation of the amino nitrogen ofthe 5-amino-2-benzylmercapto-1,3,4-thiadiazole (step b) is performedaccording to ways similar to the steps a)and a')of the precedingschemes.

The acylating agent of the step ah which is the phthalimidocarboxylicacid chloride, corresponding to the desired group Y, is obtained(step 1) through treatment of the corresponding carboxylic acid withthionyl chloride; the phthalimidocarboxylic acid can be in turn preparedaccording to two different ways (step m and step i): either by reactionof potassium phthalimide with a halogenated carboxylic acid of theformula

    X--R.sub.1 --COOH

or by reaction of phthalic anhydride with an amino acid of the formulaNH₂ --R₁ --COOH.

After the acylation step a), the synthesis proceeds through the samesteps as those of the preceding case (steps b and c).

For the preparation of the compounds of the series II and III (theN-methyl derivatives), first of all the acylation is performed of the5-amino-2-benzylmercapto1,3,4-thiadiazole (obtained through benzylationaccording to the step d) of the Scheme A). According to the desiredmeaning of the group Y, the scheme A, steps d)and a'), or a and e), thescheme B, steps d)and a) the scheme C, step h) or step a) are followed.The product obtained from Such operations can be represented by thefollowing formula: ##STR14## wherein Y' is Y in case the terminal groupis an ester or an acid (scheme A) and in case the terminal group is aphthalimido group (scheme C). In case the terminal group is an aminogroup (scheme B), Y' is X (a halogen), as the amino group will beintroduced at the end by means of treatment with ammonia.

The compound of the preceding formula is subjected to a methylationreaction which is pointed out by "n" in the scheme D illustrated below.##STR15##

The methylation reaction is performed by dissolving the compound in ananhydrous organic solvents generally THF, containing sodium hydride in aslight stoichiometric excess.

Then methyl iodide is added while keeping the mixture stirred undernitrogen. After completion of the reaction, the two methyl derivativesare separated by column thromatography.

The two methyl derivatives are then oxidized and transformed intosulfonamide under the same conditions disclosed for the derivatives ofthe series I (steps b and c, or steps b' and c').

According to a different embodiment of this invention, the compounds ofseries I in which Y is the group

    R.sub.2 OCO--R.sub.1 --

can be prepared by making use of acetazolamide as a starting material,instead of 5-amino-2-mercapto-1,3,4-thiadiazole. In this caseacetazolamide is first of all hydrolyzed so as to eliminate the amidegroup bound in the 5th position and to leave, in place thereof , anamine group. The resulting compound is then acylated in its aminicgroup, while no transformation is required for the group bound in the2nd position, which is already the one desired.

The above method is illustrated in the following scheme E: acetazolamide(5-acetamido-2-sulfonamido-1,3,4-thiadiazole) is subjected to acidhydrolysis (step o), followed by neutralization of the resulting acidsolution up to precipitation of 5-amino-2-sulfonamido-1,3,4-thiadiazole(step p). ##STR16##

Thereafter, 5-amino-2-solfonamido-1,3,4-thiadiazole is acylated (step q)by means of a hemiester hemialide of the bicarboxylic acid correspondingto the desired group, i.e.

    R.sub.2 OCO--R.sub.1 --COX

wherein X is a halogen atom and R₂ is different from hydrogen. In theparticular case that the final product desired is a free carboxilic acid( R₂ =H), the process described above is completed by a further step fordeblocking the carboxylic group, through a prolonged treatment with astrong alkali.

Other possible acylating agents for carrying out step q) are thehemiesters of the carboxylic acid at issue, i.e. the compounds of theformula:

    R.sub.2 OCO--R.sub.1 --COOH

or their anhydrides: ##STR17## or their cyclic anhydrides of theformula: ##STR18## or else the corresponding asymmetric diesters:

    R.sub.2 OCO--R.sub.1 COOR'--

As already mentioned in the disclosure of the first group of methodsaccording to the invention, the acylation reaction is carried out inanhydrous conditions, into organic solvents such as THF or CH₂ Cl₂ andunder nitrogen and employing as a catalist an organic base, preferablytriethylamine with a small amount of 4-DMAP.

An example of preparation of an acylating agent where in X is Cl is theone employing the only choloride (SOCl₂) for alogenating a hemiestercorresponding to the desired group Y, according to the scheme:

    R.sub.2 OCO--R.sub.1 --COOH+SOCl.sub.2 →R.sub.2 OCO--R.sub.1 --COCl

The manufacturing process that starts from acetazo1 amide . comparedwith the processes first described, has the advantage that it requires,as a starting material , a readily available commercial product of alimited cost, i.e. acetazolamide. Therefore the process can be carriedout in a quite simple way. The total yield obtainable is about 40%.

This invention will be disclosed in the following for exemplificationand not for limitative purposes, with reference to the followingpreparative examples.

EXAMPLE 1 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende023)

Series I, Y=CH₃ OCO(CH₂)₂ --

Scheme A, Route Steps (a), (b), (c) (a) Preparation of5-methylsuccinoylamino-2-mercapto1,3,4-thiadiazole

5 g of 5-amino-2-mercapto-1,3,4-thiadiazole (0.037 mole) is suspended in30 ml of CH₂ Cl₂, under nitrogen at room temperature and with stirring.Then 6 ml of Et₃ N (0.043 mole),, 5,6 ml (0.037 mole) of succinoylchloride monomethyl ester and 100 mg of 4-dimethylaminopyridine (4-DMAP)are added. The reaction is checked by thin layer chromatography (TLC) onsilica gel (10% methanol in chloroform) and it shows to be completeafter 3 hours.

To obtain the purified product, a double volume (about 100 ml) of 30%NH₄ OH is added to the mixture, then it is diluted with methylenechloride and the water phase, after separation, is acidified to pH 4with concentrated hydrochloric acid without heating.

The precipitate so formed is filtered off and crystallized from ethanol,yielding 7 g of the product with melting point 183°-186° C.; yield 76%.

¹ H-NMR 60 MHz (Py): δ=2.8 (m,4H,--CH₂ CH₂ --); 3.62 (s,3H,OCH₃

IR(KBr): ν_(max) =3225, 2920, 1695, 1580, 1365, 990, 730 cm⁻¹

(b) Preparation of5-methylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole

Gaseous chlorine is bubbled through a suspension of 2 g of5-methylsuccinoylamino-2-.mercapto-1,3,4-thiadiazole in 25 ml of a watersolution of 33% acetic acid, while the mixture is kept stirred at 0° C.for 2 hours.

The sulfonyl chloride that is precipitated is filtered, then washed withice-cold water and then dried under vacuum.

2.3 g of sulfonyl chloride is obtained, which is immediately employedfor the preparation of the sulfonamide.

(c) Preparation of 5-methylsuccinoylamino-2-sulfonamido1,3,4-thiadiazole(Rende 023)

2.3 g of methylsuccinoylamino-2-sulfonylchloride1,3,4-thiadiazole isslowly added under nitrogen to 50 ml of freshly condensed liquid NH₃ at-78° C.

When the addition is complete, ammonia is removed keeping the reactionvessel at room temperature, and the residue is dried in vacuum. The rawproduct of sulfonamide is then purified through solubilization in 2N NH₄OH and subsequent precipitation by addition of concentrated HCl up to PH4.

After filtering and drying, 1.5 g of the product with melting point173°-175° C. is obtained, the yield being 60% as calculated startingfrom 5-methylsuccinoylamino-2mercapto-1,3,4-thiadiazole.

¹ H-NMR 300 MHz (DMSO--d₆): δ=2.76 (m, 4H, --CH₂ CH₂ --(3.59(s,3H,OCH₃); 8.29 (s, 2H, SO₂ NH₂)

¹³ C-NMR (DMSO--d₆): 27.8 (C-9), 29.7 (C-8), 51.5 (CH₃), 161 (C-5),164.2

(CSO₂ NH₂), 171.7 (CONH), 172.8 (CO)

IR (KBr): ν_(max) 3320, 3220, 1718, 1700, 1360, 1335, 1160, 925 cm⁻¹

Analysis (C₇ H₁₀ NO₅ S₂) calcd.: C, 28.56; H, 3.42. N, 19.04; found: C,28.23; H, 3.45; N, 1879; S, 21.45

EXAMPLE 2 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende023)

Series I, Y , CH₃ OCO(CH₂)₂ --

Scheme A, Route Steps (d), (a'), (b'), (c) (d) Preparation of5-amino-2-benzylmercapto-1,3,4-thiadiazole

10 g of 5-amino-2-benzylmercapto-1,3,4-thiadiazole is added to 300 ml of95% ethanol into which 1.7 g of sodium had been dissolved. Afterdissolution of the product, 9 ml of benzyl bromide is added withstirring and at room temperature (molar ratio 1/1). Stirring is endedafter 15 minutes during which period the formation of a whiteprecipitate is observed; the mixture is left standing overnight.

The mixture is then diluted with water and the solid matter is separatedby filtration and washed with water. After crystallization from 95%ethanol, 10 g of the product with melting point 158°-161° C. isobtained, the yield being 60%.

(a') Preparation of5-methylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

2.7 g (27 mmole) of Et₃ N, 2.7 g (18 mmole) of succinoyl chloridemonomethyl ester and 100 mg of 4successively added to 4 g of5-amino-2-benzylmercapto1,3,4-thiadiazole (18 mmole) suspended in 20 mlof anhydrous methyl chloride.

The reaction mixture is kept stirred undernitrogen and is checked by TLC(10% methanol in chloroform); the reaction shows to be complete after 4hours. The reaction mixture is then diluted with 2N HCl and extractedthree times with CH₂ Cl₂. The organic extracts are washed with watertill neutral reaction and dried over Na₂ SO₄.

The raw product obtained gives after crystallization from ethanol 4.2 gof the product with melting point 156°-161° C.; yield 70%.

¹ H--NMR 60 MHz (CDCl₃): δ=2.85 (dt,4H,--Cl₂ CH₂ --); 3.65 (s,3H,OCH₄.4(s, 2H,CH₂ benzyl); 76.3 (s,5H,aryl).

IR (CHCl₃): ν_(max) 3400, 3170, 2920, 1740, 1700 cm⁻¹

(b') and (c) Preparation of5-methylsuccinoylamino-2sulfonamido-1,3,4-thiadiazole (Rende 023)

The oxidation with gaseous chlorine and the subsequent formation of5-methylsuccinoylamino-2-sulfonamid.-1,3,4thiadiazole are carried outlike those performed in Example 1, steps (b) and (c).

EXAMPLE 3 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende023)

Series I, Y=CH₃ OCO(CH₂)₂ --

Scheme A. Route Steps (a), (e), (b'), (c) (a) Preparation of5-methylsuccinoylamino-2-mercapto1,3,4-thiadiazole

The preparation is carried out as disclosed in Example 1, step (a).

(e) Preparation of 5-methylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

4 g of 5-methylsuccinoylamino-2-mercapto-1,3,4-thiadiazole is added to420 mg of sodium dissolved in 80 of 95% ethanol. After dissolution ofthe product, 22 ml of benzyl bromide is added with stirring at roomtemperature. The reaction mixture is kept in such conditions for 15minutes, during which time the formation of a white precipitate isobserved. Stirring is then stopped and the mixture is kept reactingovernight. Then the same is diluted with water, filtered and washed withwater. The solid product so obtained is purified through crystallizationfrom ethanol so as to obtain 5.2 g of benzylate; yield=86%.

(b) and (c) Preparation of the5-methylsuccinoylamino-2sulfonamido-1,3,4-thiadiazole (Rende 023)

The process is carried out according to the steps (b') and (c) of thepreceding Example.

EXAMPLE 4 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende023)

Series I, Y=CH₃ OCO(CH₂)₂ --

Scheme A, route steps (d), (a'), (e'), (b), (c) (d) and (a') Preparationof 5-methylsuccinoylamino-2benzylmercapto-1,3,4-thiadiazole

The process is carried out according to steps (d) and (a') of Example 2.

(e') Debenzylation of5-methylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

1 g of the benzylate dissolved in 100 ml of absolute EtOH is added to7.5 g of sodium. The mixture is kept under reflux till completedissolution of sodium. A further volume of 300 ml of ethanol is thenadded, and CO₂ is bubbled for 11/2 hours. Sodium carbonate so formed isfiltered off and repeatedly washed with ethanol.

Washing and filtering waters are collected and then concentrated invacuum under CO₂, and the residue is extracted three times with ethylacetate.

After solvent removal, the raw product so obtained is crystallized fromethanol yielding 440 mg of5-methylsuccinoylamino-2-mercapto-1,3,4-thiadiazole; yield=70%.

(b) and (c) Preparation of5-methylsuccinoylanino-2-sulfonamido-1,3,4-thiadiazole (Rende 023)

The process is carried out according to the steps (b) and (c) of Example1.

EXAMPLE 5 5-succinoylamino-2-sulfonamido-1,3,4-thiadiazolic, acid (Rende037)

Series I, Y =HOCO(CH₂)₂ --

Scheme A Preparation of5-methylsuccinoylamino-2-sulfonamid-1,3,4-thiadiazole (Rende 023)

The preparation is carried out according to the procedures disclosed inany one of the preceding examples.

Preparation of 5-succinoylamino-2-sulfonamido-1,3,4-thiadiazolic acid(Rende 037)

5 g of 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole isdissolved into 20 ml of 5N NAOH and kept standing for 2 hours at roomtemperature. The solution is acidified to pH 4 by adding concentratedHCl. The solid so formed is filtered off, washed with cold water andthen dried. 3.3 g of the acid is obtained with melting point 196°-198°C. and yield of 70%.

¹ H--MHz (DMSO--d₆): δ=2.68 (dt,4H,--CH₂ CH₂ --); 8.3 (s,2H,SO₂ NH₂);12.7 (s',1H,OH)

¹³ C-NMR (DMSO--d₆): 27.8(C-9), 2.95(C-8); 160.6(C-5); 163.7(CSO₂ NH₂);171(CONH); 172.9(CO)

IR (KBr): ν_(max) 3520, 3220, 1732, 1723, 1370, 1170 cm⁻¹

Elemental analysis (C₆ H₈ N₄ O₅ S₂) Calcd.: C, 25.7; H, 2.9, N, 19.98;S, 22.88; Found: C, 25.3; H, 3.15, N, 19.62; S, 22.50.

EXAMPLE 6 5-Ethylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende029)

Series I, Y=CH₃ CH₂ OCO(CH₂)₂ --

Scheme A, Route Steps (d), (a'), (b'), (c) Preparation of succinoylchloride monoethyl ester (the acylating agent)

35 ml of absolute ethanol and a catalytic amount (0.05 ml) ofconcentrated sulfuric acid are added to 5 g of succinic anhydride. Thereaction mixture is kept under reflux for 30 minutes, then it is stirredfor 20 minutes at room temperature and again for 30 minutes by heating.

The excess ethanol is evaporated and the solution is diluted with waterand then extracted with acetate. The organic extracts are washed withbrine, then dried over Na₂ SO₄ so giving, after solvent evaporation anamount of 6.3 g of succinic acid monoethyl ester.

6.3 g of the acid is kept under reflux for 3 hours at 60° C. with 4.7 mlof SOCl₂ (molar ratio 1:1.5).

The solution is distilled under reduced pressure (18 mm Hg) so obtaining4.4 g of the product (boiling point=93° C., 18 mm Hg).

(d) Preparation of 5-amino-2-benzylmercapto-1,3,4-thiadiazole

The process is carried out according to the step (d) of Example 2.

(a') Preparation of5-ethylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

4.4 ml (30 mmole) of triethylamine, 3.3 g of succinoyl chloridemonoethyl ester (20 mmole) and 100 mg of 4-dimethylaminopyridine aresuccessively added to 4.5 9 of5-amino-2-benzylmercapto-1,3,4-thiadiazole (20 mmole) suspended in 10 mlof anhydrous methylene chloride. The reaction mixture is kept stirredunder a nitrogen and a TLC is performed to follow the reaction course(5% methanol in chloroform), said reaction showing to be complete in 6hours. The mixture is then filtered, diluted with 0.2 N HCl andextracted three times with methylene chloride. The organic extracts arethen collected, washed with water till neutrality and finally dried overanhydrous sodium sulfate. The raw product so obtained is purified bycrystallization from ethanol so giving 4.9 g of the product with meltingpoint 140°-143° C. and yield of 70%.

¹ H-NMR 60 MHz (DCl₃): δ=1.2 (t,3H,CH₃); 2.88 (m,4H,--CH₂ CH₂ --); 4,1(q, 2H,OCH₂); 4,5 (s,2H,CH₂ benzyl); 7,34 (S,5H,aryl)

IR (CHCl₃): ν_(max) 3165, 2920, 1735, 1700, 1555, 1310, 1160 cm⁻¹

(b') Preparation of5-ethylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole

4 g of 5-ethylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole issuspended in 70 ml of a 33% water solution of acetic acid. The mixtureis kept stirred at 10° C. under chlorine for-three hours and a half.

The solid chloride so formed is filtered off in vacuo and then washedwith cold water and set aside to dry. 3.4 g of the raw product is thusobtained, and it is immediately employed for the next reaction.

(c) Preparation of 5-ethylsuccinoylanino-2-sulfonamide-1,3,4-thiadiazole(Rende 029)

3.4 g of 5-ethylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole isadded at -78° C. under nitrogen atmosphere to 80 ml of freshly condensedliquid ammonia. The reaction vessel is then placed in a water bath andammonia is thus removed with a nitrogen stream.

The solid residue is purified by direct crystallization with 95% ethanol(checks performed through TLC with 6% methanol in chloroform, RF about0.4). 1.7 g of the product is obtained with melting point 192°-197° C.and 50% yield starting from5-ethylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole.

¹ H-NMR 300 MHz (DMSO--d₆): δ=1,15 (t,3H,CH₃); 2,68 (t,2H,CH₂); 2,79(t,2H,CH₂); 4,05 (q,2H,OCH₂); 8,35 (s,2H,SO₂ NH₂)

¹³ C-NMR (DMSO-d₆): 14(CH₃); 28,1(C-9); 29,7(C-8); 60(C-11); 161(C-5);164,2(CSO₂ NH₂); 171,2(CONH); 171,8(C-10)

IR KBr): ν_(max) 3330, 1720, 1555, 1340, 1170, 930 cm⁻¹

Elemental analysis (C₈ H₁₂ N₄ O₅ S₂) Calcd.: C, 31.16, H, 3.92, N,18.07, S, 20.79; Found: C, 31.51, H, 4.1, N, 17.94; S, 20.44.

EXAMPLE 7 5-Pentylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende032)

Series I, Y=CH₃ (CH₂)₄ OCO(CH₂)₂ --

Scheme A, Route Steps (d), (a'), (b'), (c) Preparation of succinoylchloride monopentyl ester (the acylating agent)

5.4 ml of 1-pentanol (molar ratio 1:1) and 0.1 ml of concentratedsulfuric acid are added to 5 g of succinic anhydride. The reactionmixture is kept under reflux at 70° C. for 15 minutes, then it isstirred at room temperature for 15 minutes and it is heated again for 30minutes.

The excess alcohol is evaporated in vacuo and the reaction mixture isthen diluted with water and extracted with ethyl acetate. The organicextracts, after drying over anhydrous sodium sulfate and evaporation,yield 7.2 g of the succinic acid monopentyl ester.

The hemiester so obtained is chlorinated by treatment with 4.1 mi ofSOCl₂ (molar ratio 1:1.5) under reflux at 70° C. for 5 hours.

The chloride so formed is then distilled under reduced pressure and 6.7of the chloride is collected.

(d) Preparation of 5-amino-2-benzylmercapto-1,3,4-thiadiazole

The preparation is carried out according to the step (d) of Example 2.

(a') Preparation of5-pentylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

4.6 ml (34 mmole) of triethylamine, 4.6 ml of succinoyl chloridemonopentyl ester and 150 mg of 4-DMAP are successively added to 5 g of5-amino-2-benzylmercapto-1,3,4-thiadiazole (22 mmole) suspended in 30 mlof anhydrous CH₂ Cl₂.

The mixture is kept stirred at room temperature under inert gasatmosphere for 5 hours and the reaction is checked through TLC (6%methanol in chloroform).

The reaction mixture is neutralized with 2N HCl and is extracted threetimes with methylene chloride; the organic extracts are washed withwater and then they are dried over anhydrous sodium sulfate.

The raw product so obtained is purified by crystallization from ethanolso giving 5.3 g of the product with melting point 128°-130° C. and yieldof 60%.

¹ H-NMR 60 MHz (CDCl₃): δ=0,83 (t,3H,CH₃); 1,32 [m,6H,(CH₂)₃ ]; 2,8 (m,4H, --CH₂ CH₂ --); 4,01 (t,2H, OCH₂); 4,35 (s,2H, CH₂ benzyl); 7,32(s,5H,aryl)

IR (CHCl₃):ν_(max) 3160, 2925, 1730, 1700, 1505, 1300, 1160 cm⁻¹

(b') Preparation of5-pentylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole

5 g of 5-pentylsuccinoylamino-2-benzylmercapto-1,3,4thiadiazole issuspended in 80 ml of a 33% water solution of acetic acid. The mixtureis kept stirred at 0° C. with a constant chlorine flow for 4 hours. Thesolid chloride so formed is filtered off, washed with cold water andthen set aside to dry.

3.5 g of the sulfonyl chloride is so obtained and it is immediatelyemployed for preparing the sulfonamide.

(c) Preparation of 5-pentylsuccinoylamino-2-sulfonamido1,3,4-thiadiazole(Rende 032)

3.5 g of 5-pentylsuccinoylamino-2-sulfonylchloride 1,3,4-thiadiazole isadded at -78° C. under nitrogen to 80 ml of freshly-condensed liquidammonia.

The ammonia is removed with a nitrogen stream by dipping the flask intoa water bath, and the residue is purified through solubilization into 2NNH₄ OH (pH 8) and then through precipitation of the product by addingconcentrated HCl till reaching a pH 4. After filtration and drying, 2.2g of the sulfonamide is obtained with melting point 201°-203° C. and 48%yield starting from 5-pentylsuccinoylamino-2-benzylmercapto-1,34-thiadiazole.

¹ H-NMR 300 MHz (DMSO-d_(d)): δ=0,80 (t,3H,CH₃); 1,2 (s,4H, (CH₂)₂pent); 1,55 (t,2H,OCH₂ --CH₂); 2,75(dt,4H,--CH₂ CH₂ --); 4,0 (t,2H,OCH₂); 8,4 (s,2H,SO₂ NH₂)

¹³ C-NMR (DMSO-d₆): 13,7(CH₃), 21,7(C-14), 27,5(C-12), 28(C-9),28,1(C-13), 29,8(C-8), 64(C-11), 161(C-5), 164,2(CSO₂ NH₂), 171,2(CONH),171,8(CO)

Elemental analysis (C₁₁ H₁₈ N₄ O₅ S₂) Calcd.: C, 37.7; H, 5.18; N,15.99; S, 18.3; Found: C, 38.05; H, 5.27; N, 16.01; S, 18.10.

IR (KBr): ν_(max) 3340, 32.40, 172.0, 1710, 1550,1365,1165,930 cm⁻¹

EXAMPLE 8 5-Isobutylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole(Rende 034)

Series I, Y=(CH₃)₂ CHCH₂ OCO(CH₂)₂ --

Scheme A, Route Steps (d), (a'), (b'), (c) Preparation of succinoylchloride monoisobutyl ester (the acylating agent)

5.5 ml of isobutyl alcohol is added to 5 g of succinic anhydride (molarratio 1:1.2) together with 0.05 ml of concentrated sulfuric acid.

The reaction mixture is kept under reflux at 60° C. for 30 minutes andthen it is stirred at room temperature for 20' and then again underreflux for a further time of 30 minutes. The excess alcohol is removedin vacuo and the mixture is diluted with water and extracted with ethylacetate. The organic phase after drying over sodium sulfate gives 6.5 gof succinic acid monoisobutyl ester that is kept then under reflux with4 ml of SOCl₂ at 60° C.

The mixture yields after distillation under reduced pressure. 6.4 g ofthe product.

(d) Preparation of 5-amino-2-benzylmercapto-1,3,4-thiadiazole

The process is carried out according to the step (d) of Example 2

(a') Preparation of5-isobutylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

2.9 ml (22 mmole) of Et₃ N, 2.8 g (14 mmole) of succinoyl chloridemonoisobutyl ester and 90 mg of 4-DMAP are successively added to 3.2 g(14 mmole) of 5-amino-2-benzylmercapto-1,3,4-thiadiazole suspended in 10ml of anhydrous CH₂ Cl₂.

The reaction mixture is kept under nitrogen and the reaction Course ischecked through TLC (6% methanol in chloroform); the reaction showscomplete in 5 hours.

The mixture is then neutralized with 0,1 N HCl (5 ml) and is extractedtwice with 50 ml portions of CH₂ Cl₂. The organic extracts are thenwashed with water and dried over sodium sulfate.

After crystallization from ethanol, 2.7 g of the product is obtainedwith melting point 133°-136° C. and 50% yield.

¹ H-NMR 60 MHz (CDCl₃): δ=0,85 (d,6H, CH₃); 1,9 (m,1H,CH); 2,9 (m,4H,--CH₂ CH₂ --); 3.8 (d,2H,OCH₂); 4,35 (s,2H,CH₂ benzyl); 7,3 (s,5H,aryl)

IR (CHCl₃): ν_(max) 3400, 3160, 2940, 1730, 1700, 1555, 1305, 1160 cm⁻¹

(b') Preparation of5-isobutylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole

2 g of 5-isobutylsuccinoylamino-2-benzylmercapto1,3,4-thiadiazolesuspended in 20 ml of a 33% water solution of acetic acid is keptstirred at 0° C. under chlorine for 3 hours.

The sulfonyl chloride product so formed is then filtered off, washedwith water and set aside to dry in vacuo.

1.74 g of the product is thus obtained which is employed for the nextreaction.

(c) Preparation of5-isobutylsuccinoylamino-2-sulfonamide-1,3,4-thiadiazole (Rende 034)

1.74 g of 5-isobutylsuccinoylamino-2-sulfonylchloride 1,3,4-thiadiazoleis slowly added under nitrogen to 35 ml of freshly condensed liquidammonia at -78° C.

When the addition has been completed, the ammonia is removed keeping thereaction flask at room temperature and keeping the nitrogen flow. Theraw product so obtained is purified by solubilization in 2N NH₄ OH at pH8.5 and subsequent precipitation of sulfonamide by addition ofconcentrated HCl till machine pH 4.

After filtration and drying, 1.5 g of the product is obtained withmelting point 201°-203° C. and 85% yield starting from the benzylatedcompound.

¹ H-NMR (300 MHz) (DMSO-d₆): δ=0,85 (d,6H,CH₃); 1,85 (m,1H,CH); 2,7(t,2H,CW₂); 2,82 (t,2H,CH₂); 3,81 (d,2H,OCH₂) ¹³ C (DMSO-d₆):18,7(2CH₃); 27,1(C-12); 28,1(C-9); 29,8(C-8); 69,8(C-11), 161(C-5);164,2(CSO₂ NH₂); 171,2(CONH); 171,7(CO)

Elemental analysis (C₁₀ H₁₆ N₄ O₅ S₂) Calcd.: C, 35.7; Ho 4.79; N, 16.65; S, 19.06; Found C, 35.84; H, 4.86; N, 16.80; S, 18.98.

IR (KBr): ν_(max) 3315, 3225, 2980, 1740, 1700, 1555, 1370, 1175, 920cm⁻¹

EXAMPLE 9 5-Dodecylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende033)

Series I, Y=CH₃ (CH₂)₁₁ CO(CH₂)₂ --

Scheme A, Route Steps (d), (a'), (b'), (c) Preparation of succinoylchloride monododecyl ester (the acylating agent)

11.2 ml of 1-dodecyl alcohol is added to 5 g of succinic anhydride(molar ratio 1:1) together with 0.05 ml of concentrated sulfuric acid.The reaction mixture is kept under reflux at 70° C. for 15 minutes, thenit is stirred at room temperature for 15 minutes and again heated for 30minutes.

The excess alcohol is removed by evaporation in vacuum and the mixtureis diluted with water and extracted with ethyl acetate.

The organic extracts, after drying over anhydrous sodium sulfate andremoval of the solvent through evaporation, yield 9.7 g of the succinicacid monododecyl ester.

The monoester product so obtained is then reacted with 3.7 ml of SOCl₂(molar ratio 1:1.5) under reflux at 65° C. for 4 hours.

The excess unreacted SOCl₂ is removed by distillation from the solutionso obtained under reduced pressure, and the amount of 8.2 g of theresidue is made up of the solid-succinoyl chloride monododecyl esterwith melting point 104°-106° C.; the yield of the whole process is 54%.

(d) Preparation of 5-aminobenzylmercapto-1,3,4-thiadiazole

The process is carried out according to the step (d) of Example 2.

(a') Preparation of5-dodecylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

3.4 ml (25 mmole) of Et₃ N, 5 g (16 mmole) of succinoyl chloridemonododecyl ester and 80 mg of 4-DMAP are successively added to 3.7 g(16 mmole) of 5-amino-2-benzylmercapto-1,3,4-thiadiazole suspended in 25ml of hydrous methylene chloride.

The mixture is kept stirred under nitrogen atmosphere and the reactioncourse is checked through TLC (5% methanol in chloroform) and thereaction shows to be complete in 6 hours.

The reaction mixture is neutralized with 2 N HCl and extracted twicewith CH₂ Cl₂. The organic extracts are then washed with water and driedover anhydrous sodium sulfate.

The raw product so obtained, after crystallization from ethanol, gives4.4 g of the product with melting point 130°-133° C., and 55% yield.

¹ H-NMR 60 MHz (CDCl₃): δ=0,85 (t,3H,CH₃); 1,3 (s,20H(CH₂)₁₀); 2,9 (m,4H, --CH₂ CH₂ --); 4,1 (t,2H,OCH₂); 4,35 (s,2H,CH₂ benzyl); 7,25(s,5H,aryl)

IR (CHCl₃): ν_(max) 3400, 3165, 2920, 1732, 1700 cm⁻¹

(b') Preparation of5-dodecylsuccinoylamino-2-sulfonilchloride-1,3,4-thiadiazole

Chlorine is bubbled through a suspension of 4 g of5-dodecylsuccinoylamino -2-benzylmercapto-1,3,4-thiadiazole in 40 ml ofa 33% acetic acid solution, while the mixture is kept stirred at 5° C.for 2 hours.

The solid sulfonyl chloride is filtered off, washed with ice-cold waterand then dried in vacuo.

3.5 g of the product is obtained which is immediately employed forpreparing-sulfonamide.

(c) Preparation of5-dodecylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende 033)

3.5 9 of 5-dodecylsuccinoylamino-2-sulfonilchoride-1,3,4-thiadiazole isslowly added under nitrogen atmosphere to 60 ml of freshly condensedliquid NH₃.

When the addition is complete, ammonia Is re,-moved by leaving thereaction vessel at room temperature and bubbling through the mixture astream of nitrogen, and the raw product is checked through TLC (8%methanol in chloroform). Sulfonamide is directly crystallized fromethanol, so yielding 2.5 g of a product with melting point 184°-186° C.and 70% yield starting from 5-dodecyl-succinoylamino-2-benzylmercapto-1,3,4-thiadiazole.

¹ H-NMR 300 MHz (DMSO-d₆): δ=0,85 (t,3H,CH₃); 1,25 (m,20H,(CH₂)₁₀ ; 2.65(t, 2H, --CH₂ CO); 2,8 (t,2H,COCH₂); 4,0 (t,2H,OCH₂); 8,32 (s,2H,SO₂NH₂)

¹³ C-NMR (DMSO-d₆): 13,3(CH₃); 28,3(C-9); 29,8(C-8); 64(C-11); 161(C-5),164,2(CSO₂ NH₂); 171,2(CONH); 171,8(CO)

Analysis (C₁₈ H₃₂ N₄ O₅ S₂) calcd. : C, 48.19; H, 7.19; N, 12.49; S,14.29; found: C, 49.07; H, 7.6; N, 12.02;. S, 15.67.

IR (KBr): ν_(max) 3325, 3240, 2920, 1740, 1720, 1470, 1175, 940 cm⁻¹

EXAMPLE 10 5-Methylglutaroylamino-2-sulfonamido-1,3,4-thiadiazole (Rende030)

Series I, Y=CH₃ OCO(CH₂)₃

Scheme A, Route Steps (d), (a'), (b'), (c) (d) Preparation of 5-amino2-benzylmercapto-1,3,4-thiadiazole

The process is carried out according to step (d) of Example 2.

(a') Preparation of5-methylglutaroylamino-2-benzylmercapto-1,3,4-thiadiazole

1.9 ml (13 mmole) of Et₃ N, 1.26 ml (9 mmole) of glutaroyl chloridemonomethyl ester and 100 mg of 4-DMAP are successively added to 2 g (9mmole) of 5-amino-2-benzylmercapto -1,3,4-thiadiazole suspended in 12 mlof anhydrous CH₂ Cl₂. The mixture is kept stirred at room temperatureunder an inert.

The reaction is checked through TLC (6% methanol in chloroform) and itshows complete within 2 hours. The reaction mixture is then neutralizedwith 2N HCl and extracted twice with CH₂ Cl₂ ; the organic extracts arethen washed with water and dried over anhydrous sodium sulfate.

The raw product so obtained is purifies through crystallization fromethanol so yielding 3.02 g of the product with melting point 121°-123°C. and 96% yield.

¹ H-NMR 60 MHz (CLCl₃): δ=1,9 (m,2H,--CH₂ --); 2,5 (m,4H,(CH₂)₂); 3,5(s,3H,OCH₃); 4,3(s,2H,CH₂ benzyl); 7,3 (s,5H,aryl)

IR (CHCl₃): ν_(max) 3400, 3160, 2950, 1735, 1700, 1555, 1300 cm⁻¹

(b') Preparation of5-methylglutaroylamino-2-sulfonylchloride-1,3,4-thiadiazole

3 g of 5-methylglutaroylamino-2-benzylmercapto-1,3,4thiadiazole issuspended in 50 ml of a 33% water sol ion of acetic acid, and themixture is kept stirred at 0° C. with bubbling a constant stream ofchlorine.

The disappearance of the starting product is checked through TLC (4%methanol in chloroform) and it is shown complete within 2 hours.

The chloride so formed is filtered off, washed with cold water and driedin vacuo.

2.4 g of sulfonyl chloride is obtained which is immediately employed forthe preparation of sulfonamide,

(c) Preparation of 5-methylglutaroylamino-2-sulfonamido1,3,4-thiadiazole (Rende 030)

2.4 g of sulfonyl chloride is slowly added under nitrogen atmosphereinto 50 ml of freshly condensed liquid ammonia, at -78° C. When theaddition is complete, ammonia is removed by leaving the reaction flaskat room temperature, and the residue is dried in vacuo.

The raw sulfonamide is purified through dissolution in 2N NH₄ OH at pH8, and successive precipitation by addition of conc. HCl till pH 4.

After filtering and drying, 1.85 g of sulfonamide is obtained withmelting point 181°-184° C. and 70% yield starting from benzylthiol.

¹ H-NMR 300 MHz (DMSO-d₆): δ=1,85 (m,2H,CH₂ --); 2,4 (t,2H,CH₂); 2,55(t, 2H, CH₂); 3,6 (s,3H,OCH₃); 8,3 (s,2H,SO₂ NH₂)

¹³ C-NMR (DMSO-d₆): 19,6(C-9); 32,3(C-10), 33,7(C-8); 51,2(C-12);161(C-5); 164,2(CSO₂ NH₂); 171,6(CONH); 172,8(CO)

Analysis (C₈ H₁₂ N₄ O₅ S₂) calcd. C, 31.16; H, 3.92; N, 18.07; S, 20.79;Found: C, 31.36; H, 3.99; N, 18.43; S, 20.51.

IR (KBr): ν_(max) 3400, 3145, 2920, 1735, 1680, 1380, 1300, 1170 cm⁻¹

EXAMPLE 11 5-Trifluoroethylsuccinoylamino-sulfonamido-1,3,4-thiadiazole(Rende 039)

Series I, Y=CF₃ CH₃ OCO(CH₂)₂ --

Scheme A, Route Steps (d), (a'), (b'), (c) Preparation of succinoylchloride monotrifluoroethyl ester (the acylating agent)

3.59 ml of CF₃ CH₂ OH and 0.05 ml of conc, sulfuric acid are added to 5g of succinic anhydride.

The reaction mixture is kept under reflux at 70° C. for 30 minutes, thenfor 20 minutes under stirring at room temperature, and again heated for30 minutes.

The excess alcohol is evaporated and the solution is diluted with waterand extracted with acetate.

The organic extracts are then washed with brine, and then dried oversodium sulfate so giving after evaporation of the solvent, 7.3 g of thesuccinic acid monotrifluoroethyl ester.

7.3 g of the acid is then treated under reflux for 5 hours at 70° C.with 4 ml of SOCl₂ (molar ratio 1/1.5).

The solution is distilled under reduced pressure so giving 5.5 g of theproduct.

(d) Preparation of 5-amino-2-benzylmercapto-1,3,4-thiadiazole

The process is carried out according to step (d) of Example 2.

(a') Preparation of5-trifluoromethylsuccinoylamino-2benzylmercapto-1,3,4-thiadiazole

5.26 ml (38 mmole) of triethylamine, 5.5 g of succinoyl chloridemonotrifluoroethyl ester (25 mmole) and 120 mg of 4-DMAP aresuccessively added to 5.6 g of5-amino-2-benzylmercapto-1,3,4-thiadiazole (25 mmole) suspended in 37 mlof anhydrous CH₂ Cl₂.

The reaction mixture is kept stirred under nitrogen atmosphere and thereaction course is checked through TLC (5% methanol in chloroform), thereaction being complete within 4 hours.

The reaction mixture is filtered, then diluted with 0.2 N HCl andextracted three times with methylene chloride. The organic extracts arethen collected together and washed with water, and then they are driedover anhydrous sodium sulfate. The raw product so obtained is purifiedthrough crystallization from ethanol so giving 7.46 g of the productwith melting point 169°-173° C. and 73% yield.

¹ H-NMR 80 MHz (DMSO-d₆): δ=2,6 (s,4H,--CH₂ CH₂ --); 4,4 (s,2H,CH₂benzyl); 4,7 (q,2H,OCH₂); 7,4(s,5H,aryl)

IR (CHCl₃): ν_(max) 3160, 2950, 1730, 1710, 1300, 1150 cm⁻¹

(b') Preparation of5-trifluoroethylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole

5 g of 5-trifluoroethylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazoleis suspended in 70 ml of a 33% acetic acid water solution. The mixtureis kept stirred at 5° C. under chlorine atmosphere for 4 hours. Thesolid chloride so formed is filtered in vacuo, washed with cold waterand dried. 2.6 g of the raw product is obtained which is immediatelyemployed for the subsequent reaction.

(c) Preparation of5-trifluoroethylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende039)

2.6 g of5-trifluoroethylsuccinoylamino-2-sulfonylchloride-1,3,4-thiadiazole isadded to 60 ml of freshly condensed liquid ammonia at -78° C. undernitrogen atmosphere. When the addition is complete, ammonia is removedwith a nitrogen stream while the reaction vessel is kept within a waterbath.

The residue so obtained is not identified as the compound shows to bevery unstable and becomes very easily hydrolysed.

EXAMPLE 12 5-(5-Aminovaleroylamino)-2-sulfonamido-1,3,4-thiadiazole(Rende 027)

Series I, Y=NH₂ (CH₂)₄ --

SCHEME B (c) Preparation of5-chlorovaleroylamino-2-benzylmercapto-1,3,4-thiadiazole

1.5 ml (13 mmole) of Et₃ N, 1.38 g of 5-chlorovaleroyl chloride and 80ml of 4-DMAP are successively added to 2 g of 5-amino-2-benzylmercapto-13,4-thiadiazole (8.9 mmole) suspended in 5 ml of anhydrous methylenechloride at room temperature with stirring and under nitrogenatmosphere. The reaction is checked by TLC (10% methanol in chloroform)and it is complete after 3 hours. The solid product so formed isfiltered, washed with water and purified by crystallization fromethanol. 2.7 g of5-chlorovaleroylamino-2-benzylmercapto-1,3,4-thiadiazole is obtainedwith melting point 145°-148° C. and 90% yield.

¹ H-NMR 60MHz (CDCl₃): δ=1,9 (m,4H,--CH₂ CH₂ --); 2,78 (t, 2H, CH₂ CO);3,69 (t,2H,CH₂ Cl); 4.5 (s, 2H, CH₂ benzyl); 7,36 (s,5H, aryl).

IR (CDCl₃): ν_(max) 3.160, 1700, 1555, 1305 cm⁻¹

(b) and (c) Preparation of5-(5-aminovaleroylamino)-2-sulfonamide-1,3,4-thiadiazole (Rende 027)

The preparation of5-(5-aminovaleroylamino)-2-sulfoamide-1,3,4-thiadiazole is performedstarting from 2 g of5-chlorovaleroylamino-2-benzylmercapto-1,3,4-thiadiazole and it followsthe synthesis route already disclosed in example 1 through the formationwith chlorine in acid medium of the corresponding sulfonyl chloride andsubsequent reaction with liquid ammonia. The raw product so obtained iscrystallized directly from 95% ethanol so yielding 750 mg of the productwith melting point 209°-212° C. and 45% yield.

¹ H-NHR 80 MHz (DMSO-d₆) δ=1,7 (m,4H,--CH₂ CH₂ --); 2,5 (t,2H,--CH₂ CO);3,6 (t,2H, CH₂ NH₂); 8,3 (s,2H,SO₂ NH₂).

IR (KBr): ν_(max) 3360, 3200, 3100, 1690, 1565, 1380, 1175, 910 cm⁻¹

Analysis (C₇ H13N₅ O₃ S₂) Calcd.: C, 30.09; H, 4.69; N, 25.07; S, 22.96;Found: C, 29.74; H, 4.29; N, 22.17; S, 21.90.

EXAMPLE 13 5-Phthalimidobutynoylamino-2-sulfonamido-1, 3,4-thiadiazole(Rende 031) ##STR19## Scheme C, route steps (i), (e), (a), (b), (c) (i)Preparation of gamma-phthalimidobutyric acid

2 g of gamma-aminobutyric acid is reacted with an equimolar amount (2.87g) of phthalic anhydride by dry melting at 150° C. The reaction productis crystallized from ethanol/water (1/2) so yielding 4 g ofgamma-phthalimidobutyric acid with melting point 120°-123° C. and 88%yield.

(1) Preparation of 5-phthalimidobutyroyl chloride

1 g of gamma-phthalimidobutyric acid Is reacted with 0.45 ml of thionylchloride (1/1.5 molar ratio) at 70° C. for 5 hours. The excess thionylchloride is then removed In vacuo and the residue is purified bycrystallization from xylene/petroleum ether 30°-50° C. (1/2 ratio). 950mg of phthalimidobutyric chloride is obtained with 77% yield.

(a) Preparation of5-phthalimidobutynoylamino-2-benzylmercapto-1,3,4-thiadiazole

0.8 ml (5.7 mmole) of triethylamine, 950 mg (3.8 mmole) of5-phthalimidobutyroyl chloride and 100 mg of 4-DMAP are added undernitrogen atmosphere to 845 mg (3.8 mmole) of5-amino-2-benzylmercapto-1,3,4-thiadiazole suspended in 10 ml of CH₂Cl₂.

The reaction mixture is neutralized with 0.1 N HCl after 3 hours andthen It is extracted with CH₂ Cl₂. The organic extracts are then washedwith water and dried over sodium sulfate. After removal of the solvent,the raw product is crystallized from ethanol so yielding 660 mg of5-phthalimidobutynoylamino-2-benzylmercapto-1,3,4thiadiazole withmelting point 128°-131° C. and 40% yield. 420 mg of5-amino-2-benzylmercapto-1,3,4-thiadiazole (50% is recovered fromcrystallization waters.

¹ H-NMR (80 MHz) (CDCl₃): δ=2,25 (m,2H,CH₂); 2,7 (t,2H,CH₂ CO); 4,18(t,2H,NCH₂); 4,5 (s,2H,CH₂ benzyl); 7,3 (d,5H, aryl); 7,8 (m,4H,phthsPimide)

(b) Preparation of5-phthalimidobutynoylamino-2-sulfonylchloride-1,3,4-thiadiazole

A suspension of 600 mg of5-phthalimidobutyroylamino2-benzylmercapto-1,3,4-thiadiazole in 12 ml ofacetic acid (33% water solution) is kept at 0° C. under chlorineatmosphere for 3 hours. During that period changes are observed in theappearance of the solid; the excess chlorine present in the reactionmedium is then removed and the solid is filtered off and washed withcold water. 550 mg of raw sulfonyl chloride is obtained which isemployed for the next reaction.

(c) Preparation of5-phthalimidobutynoylamino-2-sulfonamido-1,,4-thiadiazole (Rende 031)

550 mg of sulfonyl chloride is added slowly and under nitrogenatmosphere into 20 ml of freshly condensed liquid ammonia at -78° C.When the addition is complete, ammonia is removed putting the reactionflask into a water bath at room temperature.

The raw sulfonamide so obtained is purified through dissolution of theresidue in 2N NH₄ OH and subsequent acidification to pH 4 by addition ofconc. HCl until reaching pH 4.

After filtering and drying the precipitate, 100 mg of the product isobtained with melting point 226°-229° C. and 31% yield starting from thecorresponding benzyl compound.

¹ H-NMR 300 MHz (DMSO-d₆): δ=2,2 (q,2H,CH₂); 2,7(t,2H,CH₂ CO); 4,1(t,2H,NCH₂); 7,8 (m,4Hphthalim); 8,4 (s',2H,SO₂ NH₂)

IR (KBr): ν_(max) 3250, 2930, 1690, 1360, 1170 cm⁻¹

Analysis (C₁₄ H₁₃ N₅ O₅ S₂) Calcd.: C, 42.52; H, 3.31 N, 17.71; S,16.22; Found: C, 42.75; H, 3.47; N, 18.98; S, 17.51.

EXAMPLE 14 5 - Phthalimidobutynoylamino-2-sulfonamido-1,3,4-thiadiazole(Rende 031) ##STR20## Scheme C, Route Steps (m), (l), (a), (b), (c) (m)Preparation of gamma-phthalimidobutyric acid

3 g of 4-chlorobutyric acid is reacted with 4.5 g (molar ratio 1/1) ofpotassium phthalimide in 60 ml of DMF with stirring and at roomtemperature.

The reaction mixture is then treated after 2 hours by adding water andfiltering the precipitate so formed. After crystallization from ethanol,4.6 g of phthalimido butyric acid is obtained with 80% yield. (l), (a),(b) and (c) Preparation of5-phthalimidobutynoylamino-2-sulfonamida-1,3,4-thiadiazole (Rende 031)

The same steps are followed that correspond to those of the precedingexample.

EXAMPLE 155-Methylsuccinoylamino-4-methyl-2-sulfonamido-1,3,4-thiadiazole (Rende024)

Series III, Y=CH₃ OCO(CH₂)₂ --

Scheme D, Route Steps (n), (b'), (c') (n) Methylation reaction of5-methylsuccinoylamino-2benzylmercapto-1,3,4-thiadiazole

600 mg (13 mmole) of a 50 % sodium hydride oil suspension is added to 3g (9 mmole) of5-methylsuccinoyl-amine-2)benzylmercapto-1,3,4-thiadiazole (obtainedaccording to the Example 2, steps (d) and (d'), or according to theExample 3, steps (a) and (e)) dissolved into 90 ml of anhydrous THF.

8 ml of CH₃ I (molar ratio 10/1) is slowly added to the mixture withstirring under nitrogen While checking the reaction through TLC(5%methanol in chloroform).

The reaction mixture is neutralized with 2N HCl after 3 hours and thenextracted three times with ether; the organic phase is washed with waterand dried. The raw product is made up of a mixture which is purifiedthrough silica gel column chromatography eluting with ethylacetate/petroleum ether 40/60.

1.86 g of5-methylsuccinoylamino-4-methyl-2-benzylmercapto-1,3,4-thiadiazole (A)is obtained from such separation, with melting point 76°-78° C. (60%yield) and 800 mg of5-methylsuccinoyl-N-methylamino-2-benzylmer-capto-1,3,4-thiadiazole (B)(26% yield).

(A) ¹ H-NMR 60 MHz (CDCl₃): δ=2,8 (dt,4H,--CH₂ CH₂ --); 3,6 (s,3H,OCH₃);3,8 (s,3H,CH₃); 4,3 (s,2H,CH₂ benzyl) 7,2 (s,5H,aryl) IR (CHCl₃):ν_(max) 2960, 1740, 1620 c=⁻¹

(B) ¹ H-NMR 60 MHz (CDCl₃): δ=2,8 (dt,4H,--CH₂ CH₂ --); 3,63(s,3H,OCH₃); 3,7 (s,3H,CH₃); 4,4 (s,2H,CH₂ benzyl) 7,25 (s,5H,aryl)

IR (CHCl₃): ν_(max) 2970, 1735, 1675, 1410 cm⁻¹

(b') Preparation of5-methylsucinoylamino-4-methyl-2-sulfonylchloride-1,3,4-thiadiazole

Chlorine is bubbled through a suspension of I g of5methylsuccinoylamino-4-methyl-2-benzylmercapto-1,3,4-thiadiazole in 15ml of a 33% acetic acid water solution while the mixture is kept understirrin, at 1° C.

The reaction is checked through TLC (40% acetate in petroleum ether) andit is shown to be complete within 2 hours. The chloride so formed isextracted with methylene chloride, the organic phase is washed at 0° C.with a NaHCO₃ saturated solution and next with water until it is neutraland finally dried over sodium sulfate. 920 mg of the product is obtainedwhich is immediately employed for the subsequent reaction.

As already discussed in the preceding disclosure, a particular care isto be taken in checking the temperature during preparation, because ofthe instability of sulfonyl chloride in compounds of the series II andIII.

(c') Preparation of5-methylsuccinoylalino-4-methyl-2-sulfonamido-1,3,4-thiadiazole (Rende024)

900 mg of 5-methylsuccinoylamino-4-methyl-2-sulfonylchloride-1,3,4-thiadiazole dissolved in 5 ml of anhydrous THF is slowlyadded under nitrogen to 25 ml of freshly condensed liquid ammonia at-78° C. Ammonia is removed by leaving the reaction vessel at roomtemperature. The residue is purified by dissolution into 2N NH₄ OH andfiltration of the insoluble residue.

Waters are acidified with conc. HCl up to pH 4 and the precipitate soformed yields 320 mg of5-methylsuccinoylamino-4-methyl-2-sulfonamido-1,3,4-thiadiazole, meltingpoint 135°-137° C.; yield=38%.

¹ H-NMR 300 MHz (DMSO-d₆): δ=2,62 (t,2H,CH₂); 2,81 (t,2H,CH₂); 3,6(s,3H,OCH₃); 3,97 (s,3H,CH₃); 8,23 (s',2H,SO₂ NH₂)

IR (KBr): ν_(max) 3318, 3220, 3120, 1715, 1642, 1330, 1180 cm⁻¹

¹³ C-NMR (DMSO-d₆): 28,7(C-9) 33,7(C-8) 38,1(NCH₃) 51,2(C-11) 157,6(C-5)164,2(CSO₂ NH₂) 172,7(CO) 180,9(CONH)

Analysis (C₈ H₁₂ N₄ O₅ S₂) Calcd. C, 31.16; H, 3.92; N, 18.07; S, 20.79;Found: C, 31.70; H, 3.86; N, 18.09; S, 20.55.

EXAMPLE 16 5-Methylsuccinoyl-N-methylamino-2-sulfonamido-13,4-thiadiazole (Rende 026)

Series II, Y=CH₃ OCO(CH₂)₂ --

Scheme D, Route Steps (n), (b), (c) (n) Methylation reaction of5-methylsucinoylamino-2 benzylmercapto-1,3,4-thiadiazole

The procedure is the same as that followed in the preceding example.

(b) Preparation of5-methylsuccinoyl-N-methylamino-2-sulfonylchloride-1,3,4-thiadiazole

Chlorine gas is bubbled through a suspension of 800 mg of5-methylsuccinoyl-N-methylamino-2-benzylmercapto1,3,4-thiadiazole in 10ml of a 33% acetic acid water solution, while the mixture is keptstirred at 0° C.

The reaction is stopped after 3 hours and the reaction mixture istreated by methylene chloride extraction. The organic extracts are thenwashed with a NaHCO₃ saturated solution at 0° C. and then with water upto neutrality and finally dried over anhydrous sodium sulfate.

670 mg of an oily compound is obtained which is employed in the rawstate for the formation of the corresponding sulfonamide.

(c) Preparation of5-methylsuccinoyl-N-methylamino-2sulfonamido-1,3,4-thiadiazole (Rende026)

670 mg of5-methylsuccinoyl-N-methylamino-2-sulfonylchloride-1,3,4-thiadiazole,dissolved into 3 ml of anhydrous THF, is slowly added into 25 ml offreshly condensed liquid ammonia at -78° C. under nitrogen.

When the addition has been completed, ammonia is removed by putting thereaction vessel into a water bath at room temperature, and the residueis dissolved into 2N NH₃ at pH 8 and next precipitated by addition ofconc. HCl up to pH 4.

The precipitate so formed is filtered and dried so that 250 mg of theproduct is obtained, with melting point 120°-124° C. and 35% yieldstarting from 5-methylsuccinoyl-N-methylamino-2-benzylmercapto-1,3,4-thiadiazole

¹ H-NMR 80 MHz (DMSO-d₆): δ=2,8 (dt,4H,--CH₂ CH₂ --); 3,6 (s,3H,OCH₃);372 (s,3H,CH₃); 8,2 (s',2H,SO₂ NH₂)

IR (KBr); νmax 3300, 3250, 1750, 1660, 1350, 1175 cm⁻¹

EXAMPLE 17 5-Pentylsuccinoylamino-4-methyl-2-sulfonamido-13,4-thiadiazole (Rende 035)

Series III, Y=CH₃ (CH₂)₄ OCO(CH₂)₂ --

Scheme D, Route Steps (n), (b'), (c') (n) Methylation reaction of5-pentylsuccinoylamino-2-benzylmercapto-1,3,4-thiadiazole

500 m, (10,5 mmole) of a 50% sodium iodide oil suspension is added to 3g (7.8 mmole) of 5-pentylsuccinoamino-2-benzylmercapto-1,3,4-thiadiazole (obtained for example accordingto the Example 4, steps (d) and (a')). dissolved into 100 ml ofanhydrous THF.

10 ml of CH₃ I is slowly added to the mixture (molar ratio 10/1) withstirring under nitrogen (check performed through TLC, 2% acetone inchloroform).

The reaction is shown to be complete in 3 hours. The reaction mixture isthen diluted with 200 ml of acetate and washed first with acidifiedwater and then with water up to neutrality; the organic extracts arethen dried and the raw product is purified through silica gel columnchromatography.

1.94 g of5-pentylsuccinoylamino-4-methyl-2-benzyl-mercapto-1,3,4-thiadiazole (A)is obtained from such separation with 62% yield, as well as 870 mg of5-pentylsuccinoyl-N-methylamino-2-benzylmercapto-1,3,4-thiadiazol (B)with 27% yield.

(A) ¹ H-NMR 60 MHz (CDCl₃): δ=0,85 (t,3H,CH₃); 1,4(m,6H,(CH₂)₃);2,8(m,4H,--CH₂ CH₂ --); 3,85 (s,3H,CH₃); 4,1 (t,2H,OCH₂); 4,3 (s,2H,CHbenzyl); 7,3 (s,5H,aryl

IR (CHCl₃):νmax 2925, 1730, 1620, 1380, 975 cm⁻¹

(B) ¹ H-NMR 60 MHz (CDCl₃): δ=0.9 (t,3H,CH₃); 1,4 (m,6H,(CH₂)₃); 2.85(m,4H,--CH₂ --CH₂); 3,79 (s,3H,CH₃); 4,2 (t,2H,OCH₂); 4,5 (s,2H,CH₂benyl); 7,35 (s,5H,aryl)

IR (CHCl₃):ν_(max) 2925, 1730, 1670, 1310, 1115 cm⁻¹

(b') Preparation of5-pentylsucinoylamino-4-methyl-2-sulfonylchloride-1,3,4-thiadiazole

Chlorine is bubbled through a suspension of 1.94 g of5-methylsuccinoylamino-4-methyl-2-benzylmercapto-1,3,4-thiadiazole in 30ml of a 33% acetic acid water solution, while the mixture is keptstirred at 0° C.

The disappearance of the starting product is controlled through TLC (5%methanol in chloroform) and it shows complete within 2 hours.

The chloride so formed is extracted by means of CH₂ Cl₂, the organicphase is washed at 0° C. with a saturated solution of NaHCO₃, then withwater up to neutrality and finally it is dried over anhydrous sodiumsulfate.

The cold evaporation of the organic solvent yields 1.7 g of the productwhich is immediately employed for the next reaction.

(c') Preparation of5-pentylsuccinoylamino-4-methyl-2-sulfonamido-1,3,4-thiadiazole (Rende035)

1.7 g of 5-pentylsuccinoylamino-4-methyl-2-sulfonilchloride-1,3,4-thiadiazole dissolved into 6 ml of anhydrous THF is slowly addedto 40 ml of freshly condensed liquid ammonia at -78° C. and uddernitrogen-atmosphere. When the addition has been completed, ammonia isremoved by dipping the reaction flask into a water bath. The residue isdissolved with a 2N NH₄ OH water solution and then acidified to pH 4with conc. HCl.

An oily product is separated that is extracted twice with ethyl acetate.The organic extracts are then collected together, washed with brine,dried over anhydrous sodium sulfate and the solvent is evaporated off.Purification of the raw sulfona-nide is performed by means of silica gelcolumn chromatography, eluting with 5% methanol in chloroform. 1.12 g ofthe product is obtained with melting point 95°-97° C. and 64% yieldstarting from the benzyl product.

¹ H-NMR 300 MHz (DMSO-d₆): δ=0,85 (t,3H,CH₃); 1,27 (m,4H,--CH₂ --CH₂--); 1,55 (m.2H,CH₂); 2,65 (t,2H,CH₂ CO); 2,82 (t,2H,COCH₂); 3,92(s,3H,CH₃); 4,0 (t,2H,OCH₂); 8,26 (s,2H,SO₂ NH₂) ¹³ C-NMR (DMSO-d₆):13,7(CH₃); 21,6(C-14); 27,4(C-12); 27,7(C-13); 29,1(C-9); 33,7(C-8);38,1(C-4); 63,7(C-11); 157,6(C-5); 164,2(CSO₂ NH₂); 172,2(CO); 181(CON)

IR (CHCl₃): ν_(max) 3425, 3345, 2925, 1730, 1625, 1375, 1160 cm⁻¹

Analysis (C₁₂ H₂₀ N₄ O₅ S₂) Calcd.: C, 39.55; H, 5.53; N, 15.37; S,17.59; Found: C, 39.33; H, 5.65; N, 15.16; S, 17.49.

EXAMPLE 185-Pentylsuccinoyl-N-methylamino-2-sulfonamido-1,3,4thiadiazole (Rende038)

Series II, Y=CH₃ (CH₂)₄ OCO(CH₂)₂ --

Scheme D, Route Steps (n), (b), (c) (n) Methylation reaction of5-pentylsuccinoylamino-2-benzylmercapto- 17394-thiadiazole

The procedure is the same as that followed in the preceding example.

(b) Preparation of5-pentylsuccinoyl-N-methylamino-2-sulfonylchloride-1,3,4-thiadiazole

Chlorine is bubbled through a suspension of 800 mg of5-pentylsuccinoyl-N-methylamino-II.-benzylmercapto-1,3,4-thiadiazole in15 ml of a 33% acetic acid water solution, while the mixture is keptunder stirring at 0° C.

The reaction is checked through TLC (2% acetone in chloroform) and iscomplete in 4 hours.

The chloride so formed is extracted with methylene chloride, the organicphase is washed with a saturated solution of NAHCO₃ at 0° C., andsubsequently with ice-cold water upto neutrality, and finally it isdried over anhydrous sodium sulfate.

750 mg of the raw product is obtained that is employed for thesuccessive reaction.

(c) Preparation of5-pentylsuccinoyl-N-,methylamino-2-sulfonamide-1,3,4-thiadiazole (Rende038)

750 mg of sulfonyl chloride dissolved into 3 ml of anhydrous THF isslowly added into 20 ml of freshly condensed liquid arranonia at -78° C.and under nitrogen atmosphere.

Ammonia is removed at room temperature and the residue is dissolved into2N NH₄ OH.

The solution acidified with conc. HCl up to pH 4 , is extracted twicewith ethyl acetate and the organic phase is dried over anhydrous sodiumsulfate.

The purification of the sulfonamide is carried out through silica gelcolumn chromatography, eluting with 2% acetone in chloroform.

145 mg of the product is obtained with melting point 83°-87° C. and 20%yield starting from5-pentylsuccinoyl-N-methylamino-2-benzylmercapto-1,3,4-thiadiazole.

EXAMPLE 19 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende023)

Series I, Y=CH₃ OCO(CH₂)₂ --

SCHEME E (o) and (p) Preparation of 5-amino-2-sulfonamido-i3,4-thiadiazole

17 g of acetazolamide (purchased from Aldrich) is hydrolyzed with 150 ml10% HCl. The reaction is kept under reflux and stirred, and is monitoredby means of TLC (20% methanol in chloroform). After 5 hours the reactionshows to be complete.

The reaction mixture is cooled to room temperature and neutralized withNaOH up to pH 6. After precipitation and filtration under vacuum 12 g of5-amino-2-sulfonamido-1,3,4-thiadiazole is obtained, with yield of 87%.

(q) Preparation of5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole

12 g of 5-amino-2-sulfonamido-1,3,4-thiadiazole is suspended in 60 ml ofanhydrous CH₂ Cl₂ ; 8.7 ml of Et₃ N, 170 mg of 5-DMAP and, slowly, 6.5ml of succinoylchloride monomethyl (3-carbomethoxy-propionylchloride)are then added to such suspension.

The reaction, kept under nitrogen, is followed through TLC (20% methanolin chloroform) and shows to be complete after 5 hours.

In order to obtain the purified product, 40 ml of 25% NH₄ OH is added tothe reaction mixture and after separation, the aqueous phase isacidified with 37% HCl up to pH 4.

The precipitate so formed is filtered and crystallized from water. 13 gof the final product is obtained, with a yield of 66%.

EXAMPLE 20 5-succinoylamino-2-sulfonamido-1,3,4-thiadiazoic acid (Rende037)

Series I, Y=HOCO(CH₂)₂ --

SCHEME E Preparation of5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole (Rende 023)

The preparation is carried out according to example 19. Preparation of5-succinoylamino-2-sulfonamido-1 3,4-thiadiazoic acid (Rende 037)

13 g of 5-methylsuccinoylamino-2-sulfonamido-1,3,4-thiadiazole isdissolved in 150 ml of 5% NAOH. The reaction is kept under stirring at60° C. for 1 hour and 30 min. and is followed by means of TLC (40%methanol in chloroform).

The reaction mixture is then cooled and acidified with 5N HCl up toprecipitation of the product. The solid so formed is filtered, washedwith water and dried. 8.6 g of the final product is obtained, with ayield of 70%.

This invention has been disclosed, just for illustrative and not forlimitative purposes, according to some preferred embodiments of thesame, but it is to be understood that modifications and/or changes canbe brought in by those who are skilled in the art without departing fromits true the spirit and scope.

We claim:
 1. A method for topically treating glaucoma comprisingapplying to the eye an effective amount of a compound of the formula:##STR21## wherein Y is one of the following groups: ##STR22## wherein R₁is a straight or branched alkylene or arylalkylene, or a phenylene, R₂is hydrogen or a straight or branched alkyl possibly substituted withhalogen, R₃ and R₄, which can be the same or different from each other,are hydrogen or straight or branched alkyl, and the physiologicallyacceptable salts thereof.
 2. The method according to claim 1, wherein Yis the group: ##STR23## wherein R₂ is hydrogen or a straight or branchedalkyl having 1-20 carbon atoms and possibly substituted with halogen,and n is an integer between 1 and
 10. 3. The method according to claim1, wherein Y is the group: ##STR24## wherein R₂ is hydrogen or astraight or branched alkyl having 1-20 carbon atoms.
 4. The methodaccording to claim 1, wherein Y is the group of the formula: ##STR25##wherein R₃ and R₄, which can be the same or different from each other,are hydrogen or a lower alkyl of 1-6 carbon atoms, and n is an integerbetween 1 and
 10. 5. The method according to claim 1, wherein Y is thegroup: ##STR26## wherein R₃ and R₄, which can be the same or differentfrom each other, are hydrogen or a lower alkyl of 1-6 carbon atoms and nis an integer between 1 and
 10. 6. The method according to claim 1,wherein said compound has the formula: ##STR27## wherein Y is the group:R₂ OCO--(CH₂)_(n) --wherein R₂ is hydrogen or a straight or branchedalkyl having 1-20 carbon atoms and possibly substituted with halogen,and n is an integer between 1 and
 10. 7. The method according to claim6, wherein Y is the group:

    HOCO--(CH.sub.2).sub.2


8. The method according to claim 1, wherein said compound has theformula: ##STR28## wherein Y is one of the following groups: ##STR29##wherein R₁ is a straight or branched alkylene or arylalkylene, or aphenylene, R₂ is hydrogen or a straight or branched alkyl possiblysubstituted with halogen, R₃ and R₄, which can be the same or differentfrom each other, are hydrogen or straight or branched alkyl, and thephysiologically acceptable salts thereof.